package projectEuler;

public class Problem11 {
	public static void main(String[] args) {
		String grid = "08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08 " +
				"\n49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00 " +
				"\n81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65 " +
				"\n52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91 " +
				"\n22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80 " +
				"\n24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50 " +
				"\n32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70 " +
				"\n67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21 " +
				"\n24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72 " +
				"\n21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95 " +
				"\n78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92 " +
				"\n16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57 " +
				"\n86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58 " +
				"\n19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40 " +
				"\n04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66 " +
				"\n88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69 " +
				"\n04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36 " +
				"\n20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16 " +
				"\n20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54 " +
				"\n01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48 ";
		int field[][] = generateFieldFromGrid(grid);
		long largestProduct = determineLargestProduct(field);
		System.out.println("The largest product is: " + largestProduct);
	}

	private static long determineLargestProduct(int[][] field) {
		long largestProduct = 0;
		for(int c = 0; c < field.length; c++){
			for(int d = 0; d < field[c].length; d++){
				long rightProduct = right(field, c, d);
				long downProduct = down(field, c, d);
				long diagonalDownProduct = diagonalDown(field, c, d);
				long diagonalUpProduct = diagonalUp(field, c, d);
				if(rightProduct > largestProduct){
					largestProduct = rightProduct;
				}
				if(downProduct > largestProduct){
					largestProduct = downProduct;
				}
				if(diagonalDownProduct > largestProduct){
					largestProduct = diagonalDownProduct;
				}
				if(diagonalUpProduct > largestProduct){
					largestProduct = diagonalUpProduct;
				}
			}
		}
		return largestProduct;
	}

	private static long diagonalUp(int[][] field, int c, int d) {
		int product = 1;
		try{
			for(int i = 1; i < 5; i++){
				product *= field[c-i][d+i];
			}
		}catch(ArrayIndexOutOfBoundsException e){
			return 0;
		}
		return product;
	}

	private static long diagonalDown(int[][] field, int c, int d) {
		int product = 1;
		try{
			for(int i = 1; i < 5; i++){
				product *= field[c+i][d+i];
			}
		}catch(ArrayIndexOutOfBoundsException e){
			return 0;
		}
		return product;
	}

	private static long down(int[][] field, int c, int d) {
		int product = 1;
		try{
			for(int i = 1; i < 5; i++){
				product *= field[c+i][d];
			}
		}catch(ArrayIndexOutOfBoundsException e){
			return 0;
		}
		return product;
	}

	private static long right(int[][] field, int c, int d) {
		int product = 1;
		try{
			for(int i = 1; i < 5; i++){
				product *= field[c][d+i];
			}
		}catch(ArrayIndexOutOfBoundsException e){
			return 0;
		}
		return product;
	}

	private static int[][] generateFieldFromGrid(String grid) {
		int indexOfSpace = grid.indexOf(" ");
		int field[][] = new int[20][20];
		for(int c = 0; c < field.length; c++){
			for(int d = 0; d < field[c].length; d++){
				field[c][d] = Integer.parseInt(grid.substring(indexOfSpace-2, indexOfSpace));
				indexOfSpace = grid.indexOf(" ", indexOfSpace+1);
			}
		}
		return field;
	}
}
